The present invention relates to a method of transmission for radio monitoring via a digital mobile communication network, and more particularly to a method of transmission in which a digital GSM mobile communication system or a DCS mobile communication system is used as a transmission medium to achieve a field monitoring from a remote position. The present invention also relates to an apparatus for such transmission.
A conventional radio monitoring equipment for security and anti-theft purpose uses radio transmission to achieve a field monitoring from a remote position. A disadvantage of such conventional radio monitoring equipment is that only a limited monitoring distance within the range from 50 M to 500 M is available based on the radio frequency power for such equipment. Moreover, since such conventional radio monitoring equipment is analog transmission equipment, the transmission thereof is easily intercepted by other detection equipment. Therefore, such conventional radio monitoring equipment is not ideal in terms of the practical application effect thereof.
It is a primary object of the present invention to provide a method of transmission for radio monitoring via currently available digital mobile communication network, and a transmission apparatus for such purpose. In the method of the present invention, a digital transmission network supporting the currently available GSM mobile communication system or DCS mobile communication system is used as a medium to achieve a field monitoring from a remote position, so as to eliminate drawbacks existing in the conventional radio monitoring equipment, such as having limited monitoring distance and being subjected to interception.
The transmission apparatus of the present invention achieves the above object by adding a high-sensitivity audio amplification circuit to a mobile phone to facilitate picking up of a sound source.
The mobile phone serving as the transmission apparatus of the present invention for achieves the above object also has a DTMF decoding IC added to an incoming call loop in the mobile phone. The DTMF decoding IC reads out a DTMF code input by a caller via keys on a calling phone and verifies whether the input DTMF code is a correct password.
The mobile phone serving as the transmission apparatus of the present invention for achieves the above object also has a CPU provided with an automatic answering element for the phone to automatically answer an incoming call and send a warning sound to prompt the caller to input a password.
In the method of the present invention, the high-sensitivity audio amplification circuit is enabled only when an input password by a caller is verified as correct, in order to ensure a confidential field monitoring.
The transmission apparatus of the present invention uses a digital mobile communication system, such as GSM, CDMA, PHS, DCS or other similar system, as a transmission medium thereof, and uses DTMF decoding to control whether a caller is permitted to enable the pick-up device in the apparatus. Therefore, keypad, display and buzzer provided in regular mobile phone are removed from the transmission apparatus of the present invention.